Process for organic synthesis.



L. H. BAEKELAND & A; H. PETER.

PROCESS FOR ORGANIC SYNTHESIS. APPLICATION F|LED1uLv10,1912.

Patented July 11, 1916.

IIEO H. BAEKELND, OF YONKERS, AND ARNOLD H. PETER, OlF NEW YORK, N. Y.

PROCESS FOR ORGANIC SYNTHESIS.

To all whom-t may concern Be it known that we, Luo H. BAEKELAND, acitizen of the UnitedStates, and residing `at Yonkers, in the county ofWestchester and State' of New York, and ARNOLD H.

PETER, a citizen of the Republic of Switzerland, and residing at NewYork city, Vin the county and State of New York, have inl vented a newand useful improvement in 'y formations, which may be roughlycomparedfto the machinery of manufacture. 'llh present invention isconcerned particularly with the latter and -proviwdes a process whichmay be applied in the transformation of various elements or compounds tomore complicated compounds.

The successful commercial practice of organic synthesis has heretoforein many cases been impeded or prevented largely by difficulties in thesupply, use and results of the ancillary substances availed of ineffecting the transformation. Sometimes the repeated supply of suchsubstances has presented an important or prohibitive element of cost.Sometimes the use of the ancillary substances has involved dilicultiesin apparatus to su`ch an extent as to render the synthesis technicallyor economically impracticable on a commercial scale.` Again, the resultof using these ancillary substances has often been the production ofby-products which have icomplicated the process technically andcommercially, in some instances to such an extent as to render thesynthesis commercially impractiable.

such that the organic synthesis may be practised with apparatus which iseasily avail- 'lhese and other objects are accom- Speciicaton of LettersPatent.

. application of the generic invention.

Patented July tlf, iwf@ Application filed .Tuly 10, 1912. Serial No.708,588.

1 plished by the invention and application of a cycle of reactionscomprising in its most complete form the electrolysis of an alkali orearth alkali chlorid,.thus developing an alkali or an amalgam on thecathode and chlorin on the anode, the utilization of the chlorin toproduce hydrochloric acid and oxidation, the utilization of the acid toliberate hydrogen from the amalgam in case'an amalgam is developed (tohydrogenate or reduce the oxidized product or a further developmentthereof) and combine with the `rest of the amalgam or alkali to form achlorin. Reference is made to the development of an alkali or an amalgamon the cathode because, as will appear by illustrations, under somecircumstances it is desirable to form an amalgam to carry the hydrogento' the reduction chamber and under other circumstances the formation ofan amalgam is unnecessary and the hydrogen may be directly presented tothe substance to be reduced. As hereinafter illustrated under vario-uscircumstances the process maybe practised in forms less complete thanthat just mentioned', as, for example, by omitting either the oxidizingor acid-forming oflice of the chlorin and using it to perform only onelof said offices, obtaining the results of the performance of its otherotice elsewhere, and it is to be understood that such an omission wouldnot be a departure from the scope of the protection sought in some ofthe claims, which are not to be understood as limited by thecompleteness of this exposition. So, too, modifications -may be resortedto in the practice of the process, as, for instance, the chlorin,instead of being used to react with water and carbon, may be made toreact with other substances to produce, directly or indirectly,

hydrochloric acid, and the oxygen may be taken from the air.

' The process is hereinafter described as applied to the manufacture oftartaric acids and their compounds, and simpler'. compounds from whichthey may be developed, to which it is particularly applicable and whichrepresents a specific embodiment and Some of the didiculties heretoforeexisting in the synthetic, production of tartaric aclds andtheircompounds may be mentioned as illus-i trative of ditiiculties inthe. ractice of synthetic processes to which re erence has been made Forexample, in the electrolytic reduction of glyoxylic -acid to tartaricacid special care is taken to separate the anolyte from the cathode bymeans of a porous diaphragm. If the anolyte is an acid, it is \using asoluble chlorid as the anode liquor,

this difliculty is overcome, asbestos dia-` phragms may be used, and theprocess ben comes much easier and commercially practicable; but in thiscase chlorin is evolved as a by-product. Again, the reduction of oXalicacid to make glyoxylic acid may be accomplished by the use of potassiumamalgam in the presence of a mineral acid. This potassium amalgam ismost easily prepared bythe electrolysis of chlorid of potassium, using amercury cathode; but this, again, produces a considerable amount ofchlorin. Chlorin cannot be led to escape and its conversion into chlorinproducts would in certain cases produce an amount of such substancesconsiderably in excess of the market demand. By the process of thepresent invention the chlorin may be used for purposes of accomplishingoxidation and to produce hydrochloric acid, either or both of which maybe availed of in the synthesis, so that the chlorid may be made tosupply an agent instrumental in effecting oxidation, an agentinstrumental in effecting reduction, an agent instrumental in causingthe reducing agent to perform its office and is then recovered aschlorid Without leaving disturbing by-products.

The application of the invention to the production of tartaric acids andtheir compounds gives a process for the production of tartaric acids andtheir 'compounds of exceptional purity and at a price below that atwhich they can now be obtained and contemplates their manufacture notonly from simple carbon compounds but from carbon itself. In thisprocess is involved a succession ofreactions, some of which can beaccomplished ,in different or alternative ways or perhapssimultaneously. 'For purposes of exposition, a complete series ofreactions is described, beginning with those which occur in connectionwith the intro,- duction of the carbon, and for'convenience of referencethese are given letters, which letters correspond with those on theaccompanying drawing illustrating diagrammatically a concrete embodimentof the process.

"(A) Carbon in anylform, for instance, coke or charcoal, is introducedinto a chamber or vesselprovided with heating means. Into this vessel isconducted a colorless mixture of chlorin (which may be obtained later onin the rocess from the reaction described .in B or l) or E or all ofthem) and water, preferably in the form of steam. When 'this mixture isconducted over the carbon heated to about 300 C., there resultshydrochloric acid and carbon monoxid or carbon dioxid or a mixture ofthe two carbon-oxids. In ordinary practice, a mixture of the twocarbon-oxids will result, it being usually not whether both the acid andthe carbon-oxide l shall be used in succeeding reactions or one of themdisposed of otherwise.

(B) From the carbon-oxide formate may be obtained in a variety of ways.For example, the mixture o-f carbon monoxid and. carbon dioxid may beconducted over carbon heated to about red heat, reducing the carbondioxid in the mixture to carbon monoxid, and the carbon monoxid may beconducted over an alkali (such, for example, as caustic soda, causticpotash, or others) heated to, say, 180 to 220 C., giving a formate. O1`the carbon dioxid may be reduced to formate in a way which in itselfaffords an illustration of the process of the present invention. Thus,water in a reaction chamber may be saturated with carbon dioxid (or themixture of carbon-oxids containing it) and an amalgam, preferablyproduced by the electrolysis of a chlorid, may be caused to travel intosuch chamber, where it liberates hydrogen, reducing carbon dioxid toformate. It will be observed that when this method is followed thereactions embrace the electrolysis of a chlorid, giving chlorin and areducing agent, the utilization of the chlorin to asslst in oxidizing asubstance and the reductionpof the oxidized substance by the reducingagent. The hydrochloric acid resulting from the use of the chlorin withwater (in the form of steam) to oxidize the carbon may be used to attackthe amalgam, throw off the hydrogen from it for the reduction of thecarbon dioxid and unite with the rest of the amalgam to form chlorid. It

may under some circumstances be desirable,

to use this cycle of chlorid, chlorin and amalgam, hydrochloric acidfrom chlorin, decomposing the amalgam to form chlorid and give ofi'hydrogen, to reduce carbon dioxid obtained elsewhere. For example, itmay be, under certain circumstances, desirable to make the chlorin reactupon the carbon in thepresence of water or steam so as to producehydrochloric acid and carbon monoxid. almost exclusively (which may bemade in this manner of exceptional purity) and dispose of the-carbonmonoxid, obtaining the carbon dioxid to be reduced from Some sourceraconte not connected with the process. lt'is to be understoodthat suchuse of the cycle-of reactions with the oxidizingfeature ofv the productof the chlorid omitted is within the protection sought in some of theclaims hereinafter made.

The foregoing description of the reactions which have been designated Brepresents various ways of treating thesubstance (iXi-- dized with theassistance of the chlorin ob` oxylate by means of an amalgam, preferablyYYin an acid solution. This amalgam may be made by the electrolysis of achlorid, preferably potassium chlorid, generating chlorin at the anode,which may be mixed with steam and conducted over carbon, as hereinbeforer described in A. The amalgam thus produced may be caused to travel intoa reaction chamber containing the oxalate and an excess of hydrochloricacid which has 4been vobtained by conducting the mixture -of chlorin andsteam over carbon, as'hereinbefore Vdescribed in A. The amalgam, beingattacked" bythe 'acid in this reaction chamber, gives'o1 hydrogen,reducing the oxalate to glyoxylate,

and, after giving od' this hydrogen, combines with the hydrochloricacid'to forr'nl "chlorid, which remains in solution and may'cither belrecovered at this point and agaiii electrol'yzed or allowed to pass withtheglyoxylate into and through the transformation of the glyoxylateintol tartrate, as hereinafter set forth.

f lit will be observed that the reactions des scribed form a completecycle, which may be summed up as follows:-

slum) gives oxalic acid. The latter in presence of.

potassium amalgam and a strong acid gives glyoxylic acid x Coon c 0H+132; El Coon Coon l (E) rllhe "lyoxylate may be introduced in solutionren eredwalkaline into the cathode chamber of an electrolytic cell, theelectro- Any conlyte in the anode chamber being. preferably an alkalichlorid, although other soluble chlorids, even chlorld of hydrogen, maybe used. When the current is caused to pass' through the solution fromthe anode tothe cathode the glyoxylate is reduced to tarftrates (racemicand meso-tartrates), which are precipitated, used and worked up, as maybe desired. llf, as above suggested, the chlorid resulting from thereaction D has `been allowed Ato remain in solution with the glyoxylate,it may' be recovered after the tartrates have been precipitated, as,for' lThe alkali formed in the cathode compart` i ment may )beneutralized by the hydrochlo- .vric acid formed from the chlorin generlated in the anode compartment.

and in the various reactions willfdier according to the articularcircumstances of manufacture. n commercial practice, it will often bedesirable, for example, to store temporarily the products of the variousreactions, as, for instance, the formate or o xalate or acid or chlorid,before using them, or to connectthe various. sources of chlorin so thatthe making of the hydrochlo` ric acid or the oxidation or both may beconveniently accomplished. The process contemplates that variations willbe made in it accordingy to commercial requirements. Thus, for example,incertain manufactures some of the reactions hereinbefore described 'maybe omitted and the substances developed by such reactions obtained andintroduced otherwise. For instance, a chlorid may be electrolyzed todevelop amalgam and chlorin, the chlorin being used with steam andcarbon to give hydrochloric acid and the acid used to liberate hydrogenfrom the amal am and unite with the rest of it into chlorid, but insteadof using the carbonoxids (which may be obtained in connection with themaking of the acid) through reactions` producing therefrom oxalates oroxalic acid, the carbon-oxidsmay be disposed of otherwise4 and.v oxalicacid elsewhere obtained and introduced. rlhe course sugl gested by thisillustration'would not be a $0 Ilhe apparatus availed of in the processttt factu're of certain compounds produced therein, as formates andglyoxylates. It is to be understood that it is applicable also in othersynthetic processes.

It is particularly to be observed that in the specific embodiment of theinvention ap- 'taric acids and their compounds, comprising electrolyzinga chlorid and by means of said electrolysis both developing chlorin andpromoting the transformations hereinafter mentioned, mixing said chlorinWith Water and bringing the mixture in contact With carbon therebyoxidizing the carbon and producing hydrochloric acid, transforming thecarbon-oxid into a formic substance, the formic substance into an oxalicsubstance, the oxalic substance into a glyoxylic substance, and theglyoxylic substance into a tartaric substance,

employing 'therein the same electrolysis aforesaid whereby said chlorinis developed, and causing the hydrochloric acid produced from saidchlorin to unite With the residue from the said electrolysis to formchlorid suitable for use as aforesaid.

2. A process for the manufacture of tartaric substances, comprisingelectrolyzing a chlorid and'by means of said electrolysis developingchlorin, bringing said chlorin and Water in contact with carbon toproduce carbon-oxid and hydrochloric acid, transforming the carbon-oxidinto a tartaric substance by successive reductions wherein saidelectrolysis is employed, and causing said hydrochloric acid to unitewith the residue resulting from said electrolysis to reform chlorid.

3. A process of` manufacturing tartaric substances `comprisingdeveloping and transforming carbon into a tartaric substance byoxidation and'reduction, the oxidation being accomplished by theassistance of chlorin developed from a chlorid by electrolysis and thereduction being accomplished by means of the same electrolysis wherebythe chlorin v is produced.

4. A process of manufacturing tartaric substances comprising theoxidation and reduction of carbon, the oxidation being effected by areaction between chlorin, Water and carbon With the concomitantproduction of hydrochloric acid, the reduction being effected by theelectrolysis of a chlorid whereby the chlorin is produced and the acidbeing used to unite with the residue resulting from the electrolysis toform chlorid.

5. In a process for the manufacture of tartaric substances by theoxidation of carbon and the subsequent transformation of thecarbon-oxid, developing chlorin from a chlorid by electrolysis,conducting the chlorin With Water over carbon to Aproduce carbo-n-oxid,and reducing the carbon-oxid or a development thereof by means of thesaid electrolysis whereby the chlorin is produced.

6. In a process for the manufacture of tartaric substances byelectrolytie reduction, developing chlorin from a chlorid byelectrolysis, conducting the chlorin With water over carbon to producehydrochloric acid, and causing the said acid to react with the residuefrom the electrolysis to form chlorin.

7. A process for organic synthesis comprising eleetrolyzing an alkali orearth alkali chlorid, developing an amalgam on the cathode and chlorinon the anode, conducting a mixture of the chlorin with steam over carbonto produce carbon-oxid and hydrochloric acid, utilizing the hydrochloricacid to free hydrogen from the amalgam to reduce the carbon-oxid or adevelopment thereof and to unite with the rest Of the amalgam to formchlorid.

8. A process for organic synthesis comprising electrolyzing an alkali orearth alkali chlorid developing an amalgam and chlorin, transforming thechlorin into hydrochloric acid and carbon-oxid, reducing the carbon-oxidor a development thereof by the amalgam in the presence of thehydrochloric acid and recovering the resulting chlorid.

9. A process for organic synthesis comprising electrolyzing an alkali orearth alkali chlorid developing an amalgam and chlorin, transforming thechlorin into hydrochloric acid and earbon-oxid, reducing the carbon-oxidor a development thereof by the amalgam in the presence of thehydrochloric acid.

10. A process for organic synthesis comprising electrolyzing an alkalior earth alkali chlorid developing an amalgam and chlorin, utilizing thechlorin with Water and carbon to produce carbon-oxid, and reducing thecarbon-oxidor a development thereof by hydrogen from the amalgam.

11. A process for organic synthesis, comprising electrolyzing chlorid toproduce an amalgam and a' chlorin, developing from the chlorin undersuitable conditions the oxidation of a substance and an acid, andemploying the amalgam in the presence of the acid to reduce the oxidizedsubstance or a development thereof.

12. A process for organic synthesis com prising electrolyzing an alkalior earth alkali chlorid developing an amalgam and chlorin, conductingthe chlorin and steam over carbon to produce hydrochloric acid andcarbon-oxid, reducin the carbon-oXid or a development thereofg by meansof the amalgam in the presence of hydrochloric acid, separating thereduced substance and recovering chlorid.

13. A process for organic synthesis comprising developing from an alkalior earth alkali chlorid an amalgam and chlorin, utilizing the chlorin ineifecting the oxidation of a substance and to produce an acid,utilizing. the acid to free hydrogen from the amalgam to reduce theoxidized substance or a development thereof and to unite with the restof the yamalgam to form chlorid.

141. 1n a process for organicsynthesis, developing chlorin from alkalior earth alkali chlorid, making hydrochloric acid from the chlorin andusing the hydrochloric acid to unite With the residue of the chlorid torestore the chlorid.

15. A process for organic synthesis, comprising developing chlorin onthe anode of an electrolytic cell from a chlorid introduced therein,oxidizing a substance by suitable means embracing said chlorin, andreducing said oxidized substance or a development thereof bymeans of theelectrolysis whereby said chlorin is developed.

16. In a process for organic synthesis, developing chlorin on the anodeof an electrolytic cell from chlorid introduced therein, conducting amixture of chlorin and steam over carbon to produce hydrochloric acid,and causing the hydrochloric acid to unite with the residue left fromthe chlorid to restore the chlorid.

17. In a process for organic synthesis, electrolyzing a chlorid anddeveloping chlorin, making hydrochloric acid from the chlorin, andcausing said acid to unite With the residue left from the chlorid torestore the chlorid.

Signed at New York city, in the county of New York and State of NewYork, this 8th ,day of July, 1912. LEO H. BAEKELAND. ARNOLD H. PETER.Witnesses: i

HERMAN GUsToW, ALFRED M. HoUGH'roN.

